Cryptography and cryptology refer to encryption methods, systems and techniques for transmitting secure information communications that prevent the disclosure, loss or theft of confidential, non-public text or data information within transmitted information to unauthorized receivers of the information. Encryption is the process of encoding messages or information components thereof in such a way that only authorized senders or receivers or other persons can decode and thereby access the encoded information, which may include text messages and data in a variety of formatted or raw forms. Encryption does not of itself prevent interception of a transmitted message by unauthorized receivers, but instead denies access to encoded content information within the message to the unauthorized receiver.
In an encryption scheme, secure communication information is generally encrypted using an encryption algorithm as a function of an encryption key, to generate encoded information that may be transmitted without fear of loss of the secure information within the message as the encoded message may only be read if decrypted in a subsequent encryption algorithm step or process that uses the same key or other appropriate decryption key. An authorized recipient can easily decrypt the message by application of the decryption key, wherein interceptors or other unauthorized receivers are denied access to the secure data within the encoded message without the decryption key.
Encryption methods include symmetric key encryption and public key encryption. In symmetric key encryption, the encryption and decryption keys are the same, and senders and authorized receivers use the same key in order to encode and decode the message, respectively. Accordingly the symmetric key must be kept confidential and secure from any other unauthorized receivers in order to prevent decoding and loss of confidentiality and security of the encrypted message information content.
Public key encryption uses public and private key pairs for encryption and decryption, wherein an authorized receiver uses a cryptographic algorithm to generate their own private key from a public key and then uses their private key to decode encoded messages. Unlike symmetric key, public key encryption does not require a secure channel for an initial exchange of secret keys between the parties, and the public key may be published without compromising security. Strength of security instead depends instead on the impossibility, or computational impracticality, of an unauthorized receiver determining a properly generated private key from the corresponding public key.
Cryptographic algorithms used to generate public key are generally based on mathematical problems that admit no efficient solution, for example those inherent in certain integer factorizations, discrete logarithms, elliptic curve relationships, etc.